Hot swappable choke actuator system and/or method

ABSTRACT

A system having a choke assembly with a mandrel extending therefrom, an actuator with an actuator member extending therefrom, and a spool having a bore therethrough configured to provide a passage for the mandrel and the actuator member. The spool further includes a first end configured to be coupled to the choke assembly, a second end configured to be coupled to the actuator; and an access port formed in a wall of the spool. The system also includes a locking device configured to couple the mandrel to the actuator member within the bore of the spool. The access port is configured to receive the locking device.

BACKGROUND

There are many applications in which there is a need to control the back pressure of a fluid flowing in a system. For example, in the drilling of oil wells, it is customary to suspend a drill pipe in the wellbore with a bit on the lower end thereof and, as the bit is rotated, to circulate a drilling fluid, such as a drilling mud, down through the interior of the drill string, out through the bit, and up the annulus of the wellbore to the surface. This fluid circulation is maintained for the purpose of removing cuttings from the wellbore, for cooling the bit, and for maintaining hydrostatic pressure in the wellbore to control formation gases, prevent blowouts, and the like. In those cases where the weight of the drilling mud is not sufficient to contain the bottom hole pressure in the well, additional back pressure is applied on the drilling mud at the surface to compensate for the lack of hydrostatic head and thereby keep the well under control. Thus, in some instances, a back pressure control device is mounted in the return flow line for the drilling fluid.

To control the operating pressures within the well within acceptable ranges, a back pressure control device, such as a choke, may be operably coupled to the annulus in order to controllably bleed pressurized fluidic materials out of the annulus back into the mud tank to thereby create back pressure within the wellbore.

A choke system may include a drilling choke coupled to an actuator which controls the position of a moveable member within the drilling choke. Specifically, the actuator may be used to move a choke member between open and closed positions, or positions therebetween. The choke system may be periodically serviced to inspect and/or repair components of the choke and actuator. Drilling chokes with a close-coupled axial actuator are disassembled to remove the actuator for replacement or maintenance. The body of the choke may be opened and one or more internal components removed in order to service the choke system. Alternatively, the actuator may be dissembled to remove or repair components of the choke system. Such inspection and maintenance of the choke system may be time extensive, and therefore, costly.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a simplified schematic diagram of a choke valve useful in embodiments disclosed herein.

FIG. 2 illustrates a simplified schematic diagram of a double-acting actuator coupled to the choke system of FIG. 1 according to embodiments disclosed herein.

FIG. 3 illustrates a simplified schematic diagram of a choke valve, a double-acting actuator and a spool useful in embodiments disclosed herein.

FIG. 4 illustrates a cross-sectional diagram of the spool of FIG. 3 coupled to a choke valve and an actuator according to embodiments disclosed herein.

DETAILED DESCRIPTION

In one aspect, embodiments disclosed herein generally relate to a back pressure control device or choke system. Specifically, embodiments disclosed herein relate to a choke system having a choke assembly, an actuator, and a spool coupled between the choke assembly and the actuator and having an access port therein.

Referring to FIG. 1, an example of a choke system useful in embodiments disclosed herein is illustrated. The choke valve 1 includes a choke housing 3, a bonnet 21, a shuttle assembly 19 including a mandrel 17 and a choke member 15 slidably mounted over the mandrel 17, a trim 9 having a flanged design and serving as a seat for the choke member 15, a flange sleeve 13, and downstream trim components, such as a wear sleeve 11. The choke housing 3 includes an inlet channel 5, an outlet channel 7, and a choke orifice 27. The trim 9 is maintained in position by a seal 29, such as an O-ring, sealing the trim 9 to the housing 3. The flange sleeve 13 and the shuttle assembly 19 are aligned within the choke valve 1 with respect to an inner wall 28 of choke orifice 27, and the trim 9 is aligned with an inner wall 10 of the outlet channel 7.

For the choke valve illustrated in FIG. 1, the position of the choke member 15 may be controlled using an electronic, pneumatic, or hydraulic actuator coupled to the end of mandrel 17 extending from housing 3 or bonnet 21. For example, the back pressure applied to the fluid in inlet 5 may be controlled by the force applied to mandrel 17 by an electronic, pneumatic, or hydraulic actuator coupled to the end of mandrel 17.

As illustrated in FIG. 2, for example, the choke valve 1 may be operated with an actuator 142 which may use air or hydraulic pressure acting upon the mandrel 17 to open and close the choke member. To move the mandrel 17 toward the closed position, pressure may be applied to the “close” line 146 while venting the “open” line 148; to move the mandrel 17 toward the open position, pressure may be applied to the “open” line 148 while venting the “close” line 146.

During operation, the actuator may respond to tubular pressures, such as a measured casing pressure, and may open or close the shuttle assembly 19 accordingly. However, to obtain a required overpressure, requiring a substantial buildup in either casing pressure or hydraulic “open” pressure, may slow the response of the system. Providing an amount of pressure on the “open” line 148 while the shuttle assembly 19 is closed may serve to reduce mechanical static friction in the shuttle assembly 19 and provide faster and smoother pressure responses. For example, when the shuttle assembly 19 is in the closed position, the hydraulic control system may apply an amount of pressure to the “open” line 148. In this manner, the hydraulic pressure in the open line is biased toward open, allowing a faster response from the control system in maintaining pressure.

In addition, when closing the shuttle assembly 19, the “open” line may be reduced to a nominal pressure. After the shuttle assembly 19 is closed, the hydraulic pressure in the “open” line may be increased to a pressure less than the required pressure to initiate shuttle assembly 19 movement from the closed position, biasing the shuttle assembly 19 toward the open position. Thus, when required to open the shuttle assembly 19, the hydraulic system does not have to increase the hydraulic pressure in the “open” line as extensively to initiate shuttle assembly 19 movement. In some embodiments, the “close” line may maintain pressure when the “open” line is biased; in other embodiments, the “close” line pressure may be relaxed when the “open” line is biased.

One skilled in the art will readily appreciate that other actuators may similarly be designed to include an actuator member that may be coupled to mandrel 17 for moving the mandrel 17 and opening and closing the choke member 15.

The position of the shuttle assembly 19 within the choke system may be controlled in some embodiments by one or more electric actuators directly or indirectly coupled to the mandrel 17. In other embodiments, a linear motor directly or indirectly coupled to the mandrel 17 may directly provide a force to the mandrel 17. These and other embodiments of linear motors used with a choke system are described in more detail below.

Other embodiments of choke valves that may be useful in embodiments disclosed herein may include actuated rod systems. For example, an air or hydraulic actuator may controllably move the rod, varying shuttle assembly 19 position to control system pressure. Other embodiments of choke valves that may be useful in embodiments disclosed herein may include those described in U.S. Pat. Nos. 4,355,784, 6,253,787 and 7,004,448, assigned to the assignee of the present application and incorporated by reference herein.

Electric actuators use electromagnetism to controllably vary the position of a movable component with respect to a stationary component. Linear motors use electromagnetism to controllably vary the position or the force of a movable component with respect to a stationary component. Embodiments described herein may apply equally to linear motors and electric actuators. In some embodiments, the linear motors used in embodiments disclosed herein may include flat linear motors, tubular linear motors, or combinations thereof. Where reference may be made to flat linear motors in some embodiments, tubular linear motors may also be used, and vice versa.

A spool 100 useful in embodiments disclosed herein is illustrated in FIG. 3, which provides a coupling mechanism between a choke valve 1 and an actuator 142. As further illustrated in FIG. 4, the actuator 142 may include an actuator housing 143 and an actuator member 35 disposed in a bore 144 and extending therefrom. The spool 100 includes an access port 105 that extends from an outer surface 110 of the spool 100 to an inner surface 115 of the spool 100. In some embodiments, the access port 105 may extend through the spool 100 to be accessible from either side. A removable cover 120 may be disposed in or across the access port 105. The removable cover 120 may be a band, an insert or may be threadedly engaged with the access port 105 or any part configured to cover the access port 105. In some embodiments, the spool 100 may be a cylindrical body 125 and have a first flange 135 disposed proximate a first end of the cylindrical body 125. The spool 100 may also include a second flange 145 disposed proximate a second end of the cylindrical body 102. The first end of the cylindrical body 102 may be opposite the second end of the cylindrical body 102. The first flange 135 may be removably coupled to the choke valve 1. The second flange 145 may be removably coupled to the actuator 142. In some embodiments, the first flange 125 and the second flange 145 may be removably coupled by the use of a bolt, a shear pin, a clamping assembly, or a screw. The spool 100 may include a longitudinal bore 190 therethrough from one end of the spool to the other. The longitudinal bore 190 provides a passage for the mandrel 17 and the actuator member 35. Although shown as cylindrical, any shape may be used for the mandrel 17, actuator member 35, or longitudinal bore 190 which provides for the coupling of the choke valve 1 and the actuator 142. In other embodiments, the spool 100 may be coupled to the choke valve 1 or the actuator 142 by being integrally formed, welded, bolted or coupled by other attachment means to either the choke valve 1 or the actuator 142.

A locking device 150 may be configured to couple or secure the mandrel 17 to the actuator member 35. In some embodiments, the mandrel 17 may include a first transverse locking bore 155 disposed proximate a first end 160 of the mandrel 17 configured to receive the locking device 150. The first transverse locking bore 155 is dimensioned to receive the locking device 150 and may be at a right angle to the long axis of the mandrel 17. In some embodiments, the actuator member 35 may include a second transverse locking bore 165 disposed proximate a first end 170 of the actuator member 35 configured to receive the locking device 150. The second transverse locking bore 165 may be at a right angle to the long axis of the actuator member 35. The second transverse locking bore 165 may be aligned with the first transverse locking bore 155 to provide passage through both the mandrel 17 and the actuator member 35 for the locking device 150. In some embodiments, the second transverse locking bore 165 also includes a shoulder 175 configured to engage the locking device 150. The actuator member 35 may also include a coupling bore 180 in the first end 170 of the actuator member 35 configured to receive the first end 160 of the mandrel 17. While the actuator member 35 has been described as having a female member and the mandrel 17 has been described as having a male member that inserts into the actuator member, the actuator member 35 may have a male member that inserts into the mandrel 17 having a female member and the locking device 150 would be reconfigured for the arrangement. The first end 160 of the mandrel 17 may have more than one diameter, such that the first end 160 includes a reduced diameter to be inserted into the coupling bore 180 of the actuator member 35. The mandrel 17 may also include a shoulder which abuts the actuator member 35. The coupling bore 180 may also include a tapered recess for receiving the mandrel 17. The longitudinal bore 190 of the actuator member 35 may have more than one diameter, so dimensioned such that the mandrel 17 and the actuator member 35 pass therethrough. In another embodiment, the access port 105 could extend through the spool 100 and a pin may be used as the locking device 150. The locking device 150 may be removed by pushing it through the spool 100 (i.e., in one side and out the other).

Upon aligning the first transverse locking bore 155 and the second transverse locking bore 165, the access port 105 may also be aligned with the first transverse locking bore 155 and the second transverse locking bore 165. In some embodiments, the access port 105 is aligned with the first transverse locking bore 155 and the second transverse locking bore 165 when the choke member 15 is in a fail position. For example, in some embodiments, the access port 105 is aligned with the first transverse locking bore 155 and the second transverse locking bore 165 when the actuator 142 is in a fail-open position. In other embodiments, the locking device 150 is aligned with the first transverse locking bore 155 and the second transverse locking bore 165 when the actuator 142 is in a fail-close position.

In some embodiments, the locking device 150 may be a shear pin, a bolt or a screw. If the locking device 150 is a bolt, the bolt may include one or more positive stops to prevent incorrect installation. The one or more positive stops may be threads on the body of the bolt, a countersink, or a shoulder which may engage the shoulder 175 of the second transverse locking bore 165. The locking device 150 can be installed and removed via the access port 105.

The fail position of the actuator 142 may determine the position of the mandrel 17 and therefore the position of the choke member 15. The fail position of the actuator 142 is determined based on the structure and arrangement of the choke valve 1. A fail-open position provides the choke member 15 to operate in a full open position if the actuator 142 fails. A fail-close position provides the choke member 15 to operate in a full closed position. If the actuator 142 fails, the spool 100 allows the separation of the actuator 142 from the choke valve 1 without disassembling of the choke valve by the removal of the locking device 150. If the choke valve 1 is designed for a fail-open position, the choke valve 1 is open and may still allow fluid flow, while the actuator 142 is taken out of service by removal of the locking device 150. If the choke valve 1 is arranged for a fail-closed position, the choke valve 1 is closed and will not allow fluid flow therein, while the actuator 142 is taken out of service. In either fail position, the choke valve 1 does not have to be altered or opened up.

In some embodiments, the access port 105 in the spool 100 provides for easy removal of the locking device 150. The use of a removable spool 100 may allow the actuator 142 to be removed from the choke system without further disassembling of the choke valve 1.

To service, or otherwise access, the choke valve 1 or actuator 142, in some embodiments, a tool may be inserted into the access port 105 in the spool 100 disposed between the choke assembly 1 and the actuator 142. In some embodiments, the removable cover 120 is removed from the access port 105 prior to insertion of the tool. The locking device 150 may be removed, thereby decoupling the mandrel 17 of the choke assembly 1 and the actuator member 35 of the actuator 142. The tool may be any tool configured for removing the locking device 150 from the access port 105. In some embodiments, the tool may be a wrench, hammer, screwdriver, punch or magnet. The actuator 142 may then be serviced, replaced and/or reinstalled. To access the locking device, the access port 105 may be aligned with the first transverse locking bore 155 and the second transverse locking bore 165. In some embodiments, the first transverse locking bore 155 and the second transverse locking bore 165 will align with the access port 105 when the actuator 142 fails. In some embodiments, the actuator 142 may be fail-open or may be fail-close.

In one aspect, the embodiments disclosed herein relate to a choke system having a choke assembly, an actuator, a spool and a locking device. The choke assembly includes a choke housing having an inlet, an outlet, and a bore; a choke member disposed in the bore for controlling a flow of fluid from the inlet to the outlet, and a mandrel coupled to the choke member and extending through the housing. The actuator includes an actuator housing with a bore; and an actuator member disposed in the bore of actuator housing and extending therefrom. The spool is coupled between the choke assembly and the actuator and includes an access port extending from an outer surface of the spool to an inner surface of the spool. The locking device is configured to couple the mandrel to the actuator member.

In another aspect, embodiments disclosed herein relate to a method of servicing a choke system, the choke system comprising a choke assembly and an actuator. The method includes inserting a tool into an access port in a spool disposed between the choke assembly and the actuator; removing a locking device coupling a mandrel of the choke assembly and an actuator member of the actuator; and decoupling the actuator from the mandrel.

In another aspect, embodiments disclosed herein relate to a choke system having a choke assembly comprising a mandrel extending therefrom; an actuator comprising an actuator member extending therefrom; a spool having a bore therethrough; and a locking device coupling the mandrel to the actuator member within the bore of the spool. The spool includes a first end coupled to the choke assembly; a second end coupled to the actuator; and an access port formed in a wall of the spool.

In another aspect, embodiments disclosed herein relate to an apparatus including

-   a spool configured to couple a choke assembly to an actuator. The     spool may include an access port extending from an outer surface of     the spool to an inner surface of the spool. The apparatus may also     include a locking device configured to couple a mandrel of the choke     assembly to an actuator member of the actuator. The apparatus may     also include a first flange disposed proximate a first end of the     spool coupled to the choke assembly and a second flange disposed     proximate an opposite end of the spool coupled to the actuator. In     some embodiments, the first flange may be removably coupled to the     choke assembly and the second flange may be removably coupled to the     actuator. The spool may also include a longitudinal bore providing a     passage for the mandrel and the actuator member. The mandrel may     include a first transverse locking bore and the actuator may include     a second transverse locking bore. The first transverse locking bore     may be aligned with the second transverse locking bore. In some     embodiments, the spool may also include an access port configured to     receive the locking device, the access port may be configured to be     in alignment with the first transverse locking bore and the second     transverse locking bore. Alignment of the access port with the first     transverse locking bore and the second transverse locking bore may     occur when the choke assembly is in a fail-closed position or a     fail-open position.

In another aspect, embodiments disclosed herein relate to a method including opening an access port of a spool disposed between the choke assembly and the actuator, removing a locking device configured to couple a mandrel of the choke assembly and an actuator member of the actuator, and decoupling the actuator member from the mandrel. The method may also include removing a removable cover from the access port removing the locking device. The method may also include aligning the locking device with the access port. In some embodiments, the method includes aligning the access port of the spool with a first transverse locking port of the mandrel and a second transverse locking port of the actuator member prior to aligning the locking device with the access port. The method may also include servicing the actuator and/or coupling the mandrel to the actuator member.

In another aspect, embodiments disclosed herein relate to a system including a choke assembly comprising a mandrel extending therefrom, an actuator comprising an actuator member extending therefrom, a spool having a bore therethrough configured to provide a passage for the mandrel and the actuator member, and a locking device configured to couple the mandrel to the actuator member within the bore of the spool. The spool may further include a first end configured to be coupled to the choke assembly, a second end configured to be coupled to the actuator; and an access port formed in a wall of the spool. The access port may be configured to receive the locking device. The actuator may further include a coupling bore configured to receive the mandrel. The mandrel may further include a shoulder configured to abut the actuator member. The spool may further include a removable cover configured to be disposed in the access port. The spool may be removably coupled to the choke assembly and the actuator.

Advantageously, embodiments disclosed herein provide for servicing of the actuator without altering or opening the choke. The choke may still be operable while the actuator is serviced, replaced or repaired. Embodiments disclosed also provide for efficient removal of locking mechanisms for coupling actuators and chokes. Embodiments of locking mechanisms disclosed provide for efficient removal and installation.

Although only a few example embodiments have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without materially departing embodiments disclosed. Accordingly, all such modifications are intended to be included within the scope of this disclosure as defined in the following claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents, but also equivalent structures. Thus, although a nail and a screw may not be structural equivalents in that a nail employs a cylindrical surface to secure wooden parts together, whereas a screw employs a helical surface, in the environment of fastening wooden parts, a nail and a screw may be equivalent structures. It is the express intention of the applicant not to invoke 35 U.S.C. §112, paragraph 6 for any limitations of any of the claims herein, except for those in which the claim expressly uses the words ‘means for’ together with an associated function. 

What is claimed:
 1. An apparatus comprising: a spool configured to couple a choke assembly to an actuator, the spool comprising: an access port extending from an outer surface of the spool to an inner surface of the spool; and a locking device configured to couple a mandrel of the choke assembly to an actuator member of the actuator.
 2. The apparatus of claim 1, further comprising a first flange disposed proximate a first end of the spool coupled to the choke assembly and a second flange disposed proximate an opposite end of the spool coupled to the actuator.
 3. The apparatus of claim 2, wherein the first flange is removably coupled to the choke assembly and the second flange is removably coupled to the actuator.
 4. The apparatus of claim 1, wherein the spool further comprises a longitudinal bore providing a passage for the mandrel and the actuator member.
 5. The apparatus of claim 1, wherein the mandrel comprises a first transverse locking bore and the actuator comprises a second transverse locking bore.
 6. The apparatus of claim 5, wherein the first transverse locking bore is aligned with the second transverse locking bore to provide a passage through the mandrel and the actuator member for the locking device.
 7. The apparatus of claim 6, the spool further comprising an access port configured to receive the locking device, the access port configured to provide a further passage through the spool to the passage through the mandrel and the actuator member for the locking device.
 8. The apparatus of claim 7, wherein alignment of the access port with the first transverse locking bore and the second transverse locking bore occurs when the choke assembly is in a fail-closed position.
 9. The apparatus of claim 7, wherein alignment of the access port with the first transverse locking bore and the second transverse locking bore occurs when the choke assembly is in a fail-open position.
 10. A method comprising: opening an access port of a spool disposed between the choke assembly and the actuator; removing a locking device configured to couple a mandrel of the choke assembly and an actuator member of the actuator; and decoupling the actuator member from the mandrel.
 11. The method of claim 10, further comprising removing a removable cover from the access port prior to removing the locking device.
 12. The method of claim 10, further comprising aligning the locking device with the access port.
 13. The method of claim 12, further comprising aligning the access port of the spool with a first transverse locking port of the mandrel and a second transverse locking port of the actuator member prior to aligning the locking device with the access port.
 14. The method of claim 12, further comprising servicing the actuator.
 15. The method of claim 14, further comprising coupling the mandrel to the actuator member.
 16. A system comprising: a choke assembly comprising a mandrel extending therefrom; an actuator comprising an actuator member extending therefrom; a spool having a bore therethrough configured to provide a passage for the mandrel and the actuator member, the spool further comprising: a first end configured to be coupled to the choke assembly; a second end configured to be coupled to the actuator; and an access port formed in a wall of the spool; and a locking device configured to couple the mandrel to the actuator member within the bore of the spool, wherein the access port is configured to receive the locking device.
 17. The system of claim 16, wherein the actuator further comprises a coupling bore configured to receive the mandrel.
 18. The system of claim 16, wherein the mandrel further comprises a shoulder configured to abut the actuator member.
 19. The system of claim 16, wherein the spool further comprises a removable cover configured to be disposed in the access port.
 20. The system of claim 16, wherein the spool is removably coupled to the choke assembly and the actuator. 